Love and Rayleigh waves in nonhorizontally layered media

Abstract

A new finite element technique has been developed to study the propagation of Love and Rayleigh waves across two-dimensional nonhorizontally layered media. This new technique gives a complete analysis of the medium and the amplitudes and phases of all of the reflected and transmitted Love or Rayleigh modes. It accounts exactly for all of the incident energy. It has led to two principal new results, true for both Love- and Rayleigh-wave propagation. First, the energy propagated in the transmitted fundamental Love or Rayleigh mode through a two-dimensional nonhorizontally layered medium is exactly the same both for a direction of incidence of the wave motion on one end of the medium and on the opposite end. The amplitude of the transmitted Love or Rayleigh mode is, in general, not the same for both directions of incidence. Second, the phase velocity of the fundamental Love or Rayleigh mode through a two-dimensional nonhorizontally layered medium is exactly the same for a direction of incidence of the wave motion on one end of the medium as it is on the opposite end. Apparently different observed phase velocities arise through body-wave interference. Two models are analyzed for Rayleigh-wave motion. One is of a half-space with a step elevation and the second is of a surface layer with an inclined base overlying a half-space.